The field of the disclosure relates generally to additive manufacturing systems and, more specifically, to imaging devices for use with additive manufacturing systems and methods of imaging a build layer.
Additive manufacturing systems and processes are used to fabricate precision three-dimensional components from a digital model. Such components are fabricated using an additive process, where successive layers of material are solidified one on top of the other. At least some known additive manufacturing systems use a laser (or similar energy sources) and a series of lenses and mirrors to direct the laser over a powdered material in a predetermined pattern. Some known additive manufacturing systems include Direct Metal Laser Melting (DMLM), Selective Laser Sintering (SLS), Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM), and LaserCusing systems.
In some known additive manufacturing systems, layer and component quality is reduced due to excess heat and/or variation in heat being transferred to the metal powder by the focused laser within the melt pool. For example, sometimes local overheating occurs, particularly at overhangs, or local under heating occurs, leaving powdered build material with the solidified layer. In addition, in some known additive manufacturing systems, layer and component quality is further reduced due to the variation in conductive heat transfer between the powdered metal and the surrounding solid material of the components. For example, the melt pool produced by the focused laser sometimes becomes too large, resulting in the melted metal spreading into the surrounding powdered metal, as well as the melt pool penetrating deeper into the powder bed, thereby pulling additional powder into the melt pool and resulting in undesired contouring within the solidified layer. In addition, in some known additive manufacturing systems, the layer and component dimensional accuracy and small feature accuracy is reduced due to melt pool variations because of the variability of thermal conductivity of subsurface structures and metallic powder. As the melt pool size varies, the accuracy of the printed structures varies, especially around the edges of features.
Moreover, layer and component quality in some known additive manufacturing systems is reduced by an uneven and/or disrupted metal powder layer that is disposed on top of the previously built solidified layer. For example, from an uneven metal powder layer, the focused laser forms a contoured solidified layer. Additionally, layer and component quality in some known additive manufacturing systems is reduced through layer misalignment.
At least some known additive manufacturing systems include imaging devices to generate images of portions of the melt pool and/or solidified layer during the fabrication process. The imaging devices typically include a static camera with low exposure that tracks the focused laser to capture light during the melting process and/or a static camera that images the solidified layer. However, these imaging devices generate images of only portions of the melt pool and/or solidified layer and without reference to specific positions. Additionally, the imaging devices may be limited by their resolution to see feature changes on larger components. For example, some known imaging devices include 16 million pixels, but these are limited in resolution and capture feature changes on the layer only at a scale of approximately a millimeter, thereby limiting the device in capturing smaller feature changes. As such, early detection of problems in component quality is reduced.